A ventilation system in accordance with the present disclosure includes a housing and a core unit arranged in the housing. A fresh air inlet, an exhaust air inlet, a fresh air outlet, and an exhaust air outlet are arranged on the housing. The core unit is arranged between the inlets and outlets to transfer heat and/or humidity between fresh air and exhaust air flowing through the ventilation system. The exhaust air flows through ducting to an exhaust port in a wall of a building structure.